This invention relates to continuous casting moulds and to the use of such moulds.
Moulds which are employed in the continuous casting of steel have a mould passage extending from the inlet end to the outlet end. The shape of the mould passage is arranged to produce at the outlet end a casting of the required dimensions, and a slight taper may extend along the length of the mould passage, in the direction of casting, to counteract shrinkage of the casting during soldification.
The wall of the mould passage may be defined by one metal body of tubular form or in the case of square and rectangular sections the wall of the mould passage may be defined by four copper cooling plates which are clamped together.
In use, molten metal is introduced into the inlet end of the mould passage at such a rate as to form a liquid metal meniscus in the mould passage, and cooling is arranged so that a solid metal shell containing a liquid or "mushy" core is withdrawn from the outlet end of the mould passage.
If care is not taken, the casting can contain defects such as surface cracks and non-metallic particles and these can cause the casting to be rejected. Furthermore, bulging is a frequent defect caused by mould wear and this leads to internal cracking of the casting and rupture of the shell can occur.
It is known from EP-A-448773 to line a continuous casting mould with pieces of tiles of ceramics having resistance to wear, heat and thermal shock, heat conductivity and lubricating property, and of progressively reducing thickness to prevent the formation of air gaps between the surface of the lining and the solidifying shell, and cool the steel being cast according to a desired pattern, and/or to start solidification of the molten metal below the molten metal surface level.
Variations on this are to be found in JP-A-04123846 and JP-A-02220736 (and see also FR-A-812802).